Many telecommunication services incorporate the output of announcements and dialogs. Such types of services presuppose that the switching technology provides the functionality required for this purpose.
The switching performance features of the services which require the output of announcements and dialogs are in many cases SCP (Service Control Point) based performance features of the “intelligent network” (concept of decentralized control of services, defined in the Q.1200 series of the ITU (International Telecommunications Union)). For services associated with the intelligent network concept which provide for the output of announcements and the execution of dialogs, the provision of corresponding basic functions to which the SCP has access with the aid of the Intelligent Network Application Protocol (INAP) by a switching system is required.
However, situations detected in a switching system can also result in the direct, in other words not controlled by an SCP, output of a standard announcement (for example: “This number has not been recognized”) or an announcement including variable elements (for example: “The number you have dialed has changed, please redial using 12345”). There are moreover also dialogs whose logic or execution sequence is implemented in the switching system without SCP support. These are to be found first and foremost in the area of switching control or selection of characteristics or features for the service by the end user or in the case of services which incorporate through-connection to call centers or telephone switchboards.
The automated output of voice information, for example in the form of announcements, and the automated recognition and handling of voice information, for example for speech dialogs, requires that the telecommunication service provider or carrier makes available a corresponding functionality or corresponding resources—referred to in the following as IVR (interactive voice response) resources. IVR resources required in respect of telecommunication services comprise for example hardware elements such as computing power and storage space and also software elements such as program structures for automatic speech recognition (ASR) and for the text to speech (TTS) conversion. With regard to services having automated voice output, as a rule a user data connection is made between the subscriber and the IVR resources. It is the task of the switching facilities to establish this connection as and when required in the course of service control. The corresponding switching functions are provided by switching systems. Different solutions are available for the provision of the required resources, depending on the user data routing:
With regard to TDM (time division multiplexing) based networks, as a rule the user data stream is routed by way of the controlling switching system or the switching node. In many cases of TDM networks, therefore, the IVR resources are made available in or near a switching node. The provision of the basic functions associated with the announcement dialogs (output of recorded speech, recognition of DTMF (dual tone multiple frequency) inputs, TTS and ASR) is effected for example by means of special facilities integrated in the switching system or by means of peripheral device elements external to the switching system—often referred to as intelligent peripherals—which are situated upstream of the switching system.
With regard to packet based networks, as a rule it is only control messages for establishing and controlling the user data connection which are routed by way of the switching system, rather than the user data stream. In packet based networks, IVR resources are therefore frequently made available using a resource server (referred to as IVR server in the following) which is assigned to the switching system controlling the connection.
The development of ever more sophisticated services, with subscriber-specific features in some cases, results in greater demands on the IVR resources and/or on the IVR system. The IVR system in this situation is understood to be the device which includes the IVR resources. This can for example be one or more intelligent peripherals or an IVR server which are optionally supported by further content servers. Speech processing in particular, for example the conversion of text into speech and speech recognition, has a considerable resource requirement in respect of computing power and storage space. In addition, as the complexity of the services increases, so too does the complexity of the software required, and this has associated increased costs. The greatest possible level of efficiency of utilization of the IVR resources is therefore desirable.